Pushbutton switch with slides, having scrub action between contacts

ABSTRACT

A pushbutton switch having at least one slider operated by a pushbutton. The slider has a projection to engage a blade carrying a movable contact and move the blade and the movable contact whereby a scrubbing action is provided between the movable contact and a stationary contact when the two contacts are in engagement. The projection is beveled adjacent its distal end so that engagement between the projection and the blade is prevented when the two contacts are not in engagement.

United States Patent [72] Inventor George C. Mapelsden Easton, Conn. [21) Appl. No. 884,639 [22] Filed Dec. 12, 1969 [45] Patented June 1, 1971 [73] Assignee General Electric Company Continuation-impart of application Ser. No. 721,697, Apr. 16, 1968. This application Dec. 12, 1969, Ser. No. 884,639

[54] PUSHBUTTON SWITCH WITH SLIDES, HAVING SCRUB ACTION BETWEEN CONTACTS 6 Claims, 6 Drawing Figs.

[52] US. Cl 200/164, 200/153, 200/5 [51] Int. Cl H01h1/36, l-IOlh 3/42 [50] Field ofSearch 200/153, 12,164,5 A5 E, 159, 166.1

(56] References Cited UNITED STATES PATENTS 2,878,329 3/1959 Vermeulen ZOO/5(5) 2,968,704 l/l96l Woodward et al 200/5(E)X 3,392,250 7/1968 Ziegler et al 200/l64X FOREIGN PATENTS 1,139,185 11/1962 Germany 200/l66(.1)

549,535 10/1956 Italy 200/164 Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye Art0rney&.lohn M. Stoudt, Radford M. Reams, Ralph E. Krisher, .lr,, Frank L. Neuhauser and Oscar B. Waddell ABSTRACT: A pushbutton switch having at least one slider operated by a pushbutton. The slider has a projection to engage a blade carrying a movable contact and move the blade and the movable contact whereby a scrubbing action is provided between the movable contact and a stationary contact when the two contacts are in engagement. The projection is beveled adjacent its distal end so that engagement between the projection and the blade is prevented when the two contacts are not in engagement.

PUSIIBUTTON SWITCH WITH SLIDES, HAVING SCRUB ACTION BETWEEN CONTACTS CROSS-REFERENCE TO RELATED APPLICATION This is a eontinuationin-part of my copending application Ser. No. 72 l ,697 filed Apr. 16, 1968.

BACKGROUND OF THE INVENTION In a pushbutton switch of the type wherein a plurality of pushbuttons operate individually a plurality of switch contacts, there is frequently such low voltage across the contacts that even a slight build up of surface contamination may result in malfunction of the switch. This is particularly true when the pushbutton switch has a slider disposed between the pushbutton and the movable contact and the slider earns the movable contact out of engagement with a stationary contact. With such an arrangement, only the resiliency of the blade carrying the movable contact provides the force to bring the contacts into engagement. Although, as will become evident hereinafter, the present invention may be used with an arrangement wherein the movable contact is forcibly eammed into engagement with the stationary contact, the camming force in this latter arrangement usually provides sufficient scrubbing action to overcome surface contamination of the contacts.

Accordingly, it would be desirable, particularly in a switch of the type wherein the contacts are eammed out of engagement, to provide means to generate a scrubbing action between the contacts after they have come into engagement with each other.

SUMMARY OF THE INVENTION It is an object of this invention to provide an improved pushbutton switch.

It is another object ofthis invention to provide a pushbutton switch wherein a scrubbing action is provided between the electrical contacts to overcome contamination of the contact surfaces.

It is a further object of this invention to provide, in a pushbutton switch of the type wherein the contacts are eammed out of engagement, means to generate a scrubbing action between the contacts after they have come into engagement with each other.

Briefly stated, in accordance with one aspect of the present invention, there is provided a pushbutton switch having a hollow housing and at least one manually operable pushbutton projecting from the housing. At least one slider is disposed within the housing and is adapted for movement in response to movement of the pushbutton. At least one stationary electrical contact is disposed within the housing and at least one resilient blade, within the housing, has a fixed end and a free end. A movable contact is secured to the blade adjacent its free end. The slider is provided with means to engage and move the blade when the stationary contact is in engagement with the movable contact to provide a scrubbing action between the two contacts.

BRIEF DESCRIPTION OF THE DRAWING While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention will be better understood from the following description of the preferred embodiment taken in connection with the accompanying drawing in which:

FIG. I is a bottom view, partially cut away to show details, ofa pushbutton switch employing the present invention;

FIG. 2 is a sectional view taken along line 2-2 of FIG. I;

FIG. 3 is a sequential view illustrating the operation of the switch of FIG. I;

FIG. 4 is a view ofa part of the switch of FIG. I in modified form;

FIG. 5 is view similar to FIG. 3 but showing a switch having several blades and means to limit the scrubbing action to those blades whose contacts are in a closed position; and

FIG. 6 is a view of a part of a switch of the type shown in FIG. 5 but modified somewhat in form.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, and initially to FIGS. I and 2 thereof, there is shown a pushbutton switch 10 having a hollow housing I] defining therein an internal cavity 12. Housing II may be formed from any suitable material, it being found in practice that a moldable plastic compound is most suitable to allow the housing to be molded in the desired configuration. The open bottom of housing 11 is closed by means of a cover plate I3 which is secured to housing I] by means of staking or deforming terminals I4 and I5 at the outer surface of plate 13 and the outer surface ofhousing I I.

Terminal I4 has a portion I6 bent over to form a support for a stationary contact 17. Similarly, terminal 15 has a blade I8 secured at one end thereto. Blade 18 may be a separate piece secured to terminal US by such means as riveting or staking, or may be integrally formed with terminal I5. In any event, blade [8 has a relatively fixed end I9 where itjoins terminal l5 and a free end 20. A movable contact 21 is secured to blade 18 adjacent free end 20. Blade 18, at its connection to terminal 15, is given sufficient resiliency so that movable contact 21 is biased into engagement with stationary contact I7 until such time as a sufficient force is applied to blade 18 to move contact 21 out of engagement with contact 17. Blade 18 is given a longitudinal bend 22 throughout most ofits length to make blade 18 substantially rigid throughout its length with the flexing action of the movement of blade I8 being concentrated at fixed end I9.

A plurality of sliders 23 is disposed within cavity 12, and they are adapted for movement along their longitudinal axis, i.e., toward the right or left as viewed in FIG. I or into and out of the drawing as viewed in FIG. 2. This movement is, of course, transverse to the longitudinal axis of blade 18. Movement of sliders 23 is effected by manual movement of pushbuttons 24. Each of pushbuttons 24 has an element 25 which extends down into cavity 12 and into engagement with the upper edges of sliders 23. As is more clearly illustrated in FIG. 3, the upper edge of slider 23 is provided with cam surfaces 26 and 27 each of which is adapted to be engaged by the distal end of one of elements 25, the distal end being formed by an enlarged circular surface 28. The bottom edge of slider 23 is also provided with cam surfaces 29, 30, 31 and 32. Surfaces 29 and 30 are interconnected by an intermediate surface 33 while surfaces 31 and 32 are similarly interconnected by an intermediate surface 34.

As slider 23 is moved to the right or left as shown in FIG. 3 in response to depression of either of elements 25, blades I8 are either eammed downwardly by surfaces 33 or 34 and are held in the downward position by surfaces 29 or 32, or as slider 23 is moved in the opposite direction, the resiliency of blades 18 allows them to move upwardly along surfaces 33 or 34 until they bear against surfaces 30 or 31. Ideally, surfaces 30 and 31 will be slightly above the position which blade 18 assumes when movable contact 21 engages stationary contact I7 so that adequate engagement between the contacts is assured. Thus, in the ideal situation, blades 18 do not bear against surfaces 30 and 31 but are held slightly spaced therefrom by the engagement between contacts 17 and 21. As one of the elements 25 is moved downwardly in response to depression of a pushbutton 24, the resultant movement of slider 23 forces the other element 25 to its upward position. For example, as the element 25 bearing against cam surface 26 is moved downwardly, slider 23 moves to the right and cam surface 27 urges the other element upwardly. For further particulars on the type of pushbutton switch tow which the present improvement is applicable, reference may be had to US Pats. Nos. 2,43l,904 and 1,968,704 which are assigned to the same assignee as is the present application.

As mentioned above, with this type of arrangement wherein the resiliency of blade 18 is the force which brings contacts 17 and 21 into engagement, as opposed to those arrangements wherein the movable contact is forcibly cammed into engage ment with the stationary contact, contamination of the contact surfaces may result in inadequate electrical contact therebctween particularly when relatively low voltages and currents are being controlled by the switch. The present invention provides means to effect a scrub action between the stationary and movable contacts to overcome the build up of surface contamination.

In accordance with the present invention, means in the form of a projection 35 are provided to engage the edge of blade 18 after contact 21 has engaged contact 17. This engagement, and subsequent continued movement of slider 23 due to depression of element 25, exerts a slight sideways or transverse movement to blade 18. This latter movement provides a scrubbing action between contacts 17 and 21 after they have come into engagement with each other. Thus, the width of protection 35, i.e., the dimension between the points where projection 35 meets surfaces 30 and 31, is such that engagement between projection 35 and blade 18 is assured before circular surface 28 bottoms out at the lower extremity of surfaces 26 or 27. As the pushbutton is further depressed, the transverse movement to blade 18 is effected as circular surface 28 moves toward the lower extremity of cam surfaces 26 or 27. As the circular surface 28 bottoms out, blade 18 completes its transverse movement, and the resiliency of blade 18 will return the system to the conventional closed contact position.

To set the present invention in clearer perspective, it should be pointed out that projection 35, along with legs 36 and 37, bear against cover plate 13 with proper lubrication being provided so that a relatively friction-free sliding movement may occur therebetween. Engagement between the lower extremities of legs 36 and 37 and cover plate 13 assures proper rectilinear movement of slider 23 in response to movement of elements 25.

To provide the scrub action between the contacts, means may be incorporated into a slider which also provides the closing and opening of the contacts as illustrated in FIG. 3 or may be associated with a completely separate slider providing only the scrub action movement of the blade. In this latter arrangement, cam surfaces 29 and 32 would be obviated, and the lower edge of the slider, on each side of projection 35, would be cut back to a height of approximately that of surfaces 30 and 31. Such arrangement is shown in FIG. 4.

The operation of the arrangement illustrated in FIGS. 1-3 will be briefly described. At the top of FIG. 3, slider 23 is shown in a position wherein the blade 18 on the right side of projection 35 is in a position wherein its contact is in the closed position while the blade 18 on the left side ofprojection 35 is held in the open position by surface 29. Elements are at positions wherein the element-engaging cam surface 26 is in the normal depressed position, and the element-engaging cam surface 27 is in the normal extended position. As the pushbutton to which element 25 engaging cam surface 27 is connected is depressed, the entire system moves to the condition illustrated in the middle of FIG. 3, wherein blade 18 to the right of projection 35 has been cammed to an open position by engagement with surface 32 and blade 18 to the left of projection 35 has been allowed to flex to the closed position due to the elevated character of surface 30. At this point, the contact to the left of projection 35 is closed. However, as the pushbutton is further depressed through normal manual manipulation, the left edge of projection 35 engages the blade 18 adjacent thereto and exerts a force thereon causing it to move to the left until circular surface 28 bottoms out at the lower extremi ty of cam surface 27. As surface 28 bottoms out, one-half of the scrubbing action has been effected. The resiliency of blade 18 engaging the left side of projection 35 will return the system to the condition illustrated in the middle of FIG. 3. As the system returns to the condition illustrated in the middle of FIG. 3, the second half of the scrubbing action is effected, and

the system will remain in that condition until the other push button is depressed.

Referring now to FIG. 5, details of another modification are illustrated. In the top view, slider 40 is illustrated in the position wherein the switch is in the off" position. It is to be understood that slider 40 is one of several sliders disposed within a housing similar to housing 11 of FIG. 1. Elements 41 and 42 extend down into the housing from manually operable pushbuttons (not shown). Element 41 is the off" element while elements 42 individually effect various conditions of on" when depressed. Blade 43 carries the master switch contact so but when blade 43 is in the lower position the switch is in the off position despite the condition of any of blades 44. tile ments 41 nd 42 bear against cam surfaces 45 and 46 respectively so that whenever element 41 is depressed, slider 40 will be in the position illustrated in the top view of FIG. 5, and when any ofelcments 42 are depressed, slider 40 will be in the position illustrated in the bottom view of FIG. 5. As can be seen in FIG. 5, when element 41 is depressed, blade 43 is in the lower position thus opening the master switch whereas when any one of elements 42 is depressed blade 43 is in the upper position thus closing the master switch and making the secondary switches, operated by blades 4, effective.

It is to be understood hat blades 44 are controlled as to their opening and closing the contacts associated therewith by sliders not illustrated in FIG. 5 but operating, in response to depression of the individual elements 42, in a manner well known in the pushbutton switch art and as described in some detail above with respect to FIG. 3. Although it is not necessa ry, in accordance with the preset invention, I have chosen to illustrate the present invention in connection with a slider 40 designed to operate the master switch with respect to opening and closing and to effect scrubbing action, as in FIG. 3, of all switches.

Projections 47 and 48 are provided to perform the same function as projections 35 described above with respect to FIG. 3. Projections 48, however, are provided with a bevel 49 which causes each projection 48 to miss, or avoid engagement with, the associated blade 44 unless that blade 44 is in the closed or upper position. This can be see in he bottom view of FIG. 5 wherein the blade 44 adjacent blade 43 is engaged by its projection 48 while the remaining blades 44 are spaced from their respective projections 48 due to the bevel 49. Thus, bevel 49 assures that only those blades whose contact is in engagement with its associated stationary contact receives the scrubbing action. Exerting a scrubbing motion to a blade which does not have its movable contact in engagement with its associated stationary contact provides no benefit. On the other hand, without bevel 49 each projection 48 would engage its associated blade 44 as any of elements 42 are depressed thus necessitating a substantially greater force on the pushbutton in order to effect the operation of the switch. Moreover, through an extended period of time the blades 44 would be subjected to needless transverse stress each time the switch is operated.

Projection 47 is not provided with a bevel inasmuch as blade 43 goes into its closed position every time slider 40 is moved in response to depression of any of elements 42. Thus, blade 43 is never in an open position when projection 47 is undergoing a scrubbing movement.

It will be understood by those skilled in the art that projections 47 and 48 need not be all formed on the same slider as illustrated in FIG. 4 but may be provided on various other of the sliders within the switch housing and may, in fact, be combined with the blade opening and closing cam surfaces such as cam surfaces 29 and 30 of FIG. 3.

Although for simplicitys sake the embodiment of this invention illustrated in FIGS. 14 has been described in con nection with a switch employing only two pushbuttons, it should be apparent that it is readily adaptable for use with any number of pushbuttons and any number of sliders, as is indicated by the four pushbutton elements of FIG. 5.

To the extent that one wishes to provide a more positive means of returning the system to its normally closed position, as illustrated in the middle of PK]. 3, a separate spring means may be employed rather than relying upon the resiliency of blades 18. One such arrangement is illustrated in FIG. 4 wherein coil springs 38 and 39 are disposed between slider 23a and housing 11. Spring 38 returns slider 23a to its normal position from its right-hand position while spring 39 returns it from its left-hand position.

FIG. 6 illustrates still another embodiment, similar to that of FIG. 5 but employing a single return spring 50. The slider 40a is similar to slider 40, however, the cam surface 45, and its associated element 41, have been omitted as would be the e se in a switch omitting the master off function. Thus, depression of any of the elements 42 will move the slider 40a to the left (in FIG. 6). This will compress spring 50, which will then return the slider 40a to its normal position upon release of he previously depressed element 42. There is no need for a similar spring to the right of slider 40a, as it will never be cammed in that direction.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of construction of the examples illustrated, and it is contemplated that various other modifications or applications will occur to those skilled in the art. lt is therefore intended that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of he invention.

What 1 claim as new and desire to secure by Letters Patent of the United States is:

l. A pushbutton switch comprising: a hollow housing, at least one manually operable pushbutton projecting from said housing, at least one slider disposed within said housing and adapted for movement in response to movement of said pushbutton, at least one stationary electrical contact within said housing, at least one resilient blade within said housing having a fixed end and a free end, and at least one movable contact secured to said blade adjacent said free end, said slider having means to move said blade and thus move said movable contact out of engagement with said stationary contact in response to movement of said slider in one direction, said slider further having means to move said movable contact relative to said stationary contact to provide a scrubbing action between said contacts in response to movement of said slider in a direction opposite to said one direction.

2. The invention of claim I wherein said slider has a cam surface adjacent one edge for engagement by said pushbutton whereby said slider is moved in said opposite direction when said pushbutton is depressed.

3. The invention ol'claim 2 wherein said means to move said blade comprises a second cam surface adjacent an edge of said slider opposite said one edge and adapted to engage said blade upon movement of said slider.

4. The invention ofclaim 3 wherein said means to move said movable contact relative to said stationary contact comprises a projection on the edge of said slider which said second cam surface is adjacent to, said projection being adapted to engage and move said blade.

5. The invention of claim v4 wherein said projection is spaced from said second cam surface whereby said movable contact is allowed to engage said stationary contact prior to engagement of said blade by said projection.

6. A pushbutton switch comprising: a hollow housing, at least one manually operable pushbutton projecting from said housing, at least one slider disposed within said housing and adapted for movement in response to movement of said pushbutton, at least one stationary electrical contact within said housing, at least one resilient blade within said housing having a fixed end and a free end, and at least one movable contact secured to said blade adjacent said free end, said slider having means to engage and move said blade when said stationary contact is in engagement with said movable contact to provide a scrubbing action between said contacts. 

1. A pushbutton switch comprising: a hollow housing, at least one manually operable pushbutton projecting from said housing, at least one slider disposed within said housing and adapted for movement in response to movement of said pushbutton, at least one stationary electrical contact within said housing, at least one resilient blade within said housing having a fixed end and a free end, and at least one movable contact secured to said blade adjacent said free end, said slider having means to move said blade and thus move said movable contact out of engagement with said stationary contact in response to movement of said slider in one direction, said slider further having means to move said movable contact relativE to said stationary contact to provide a scrubbing action between said contacts in response to movement of said slider in a direction opposite to said one direction.
 2. The invention of claim 1 wherein said slider has a cam surface adjacent one edge for engagement by said pushbutton whereby said slider is moved in said opposite direction when said pushbutton is depressed.
 3. The invention of claim 2 wherein said means to move said blade comprises a second cam surface adjacent an edge of said slider opposite said one edge and adapted to engage said blade upon movement of said slider.
 4. The invention of claim 3 wherein said means to move said movable contact relative to said stationary contact comprises a projection on the edge of said slider which said second cam surface is adjacent to, said projection being adapted to engage and move said blade.
 5. The invention of claim 4 wherein said projection is spaced from said second cam surface whereby said movable contact is allowed to engage said stationary contact prior to engagement of said blade by said projection.
 6. A pushbutton switch comprising: a hollow housing, at least one manually operable pushbutton projecting from said housing, at least one slider disposed within said housing and adapted for movement in response to movement of said pushbutton, at least one stationary electrical contact within said housing, at least one resilient blade within said housing having a fixed end and a free end, and at least one movable contact secured to said blade adjacent said free end, said slider having means to engage and move said blade when said stationary contact is in engagement with said movable contact to provide a scrubbing action between said contacts. 